The following investigation of myelin-free axons derived from purified CNS myelinated axons is proposed: application of the procedure used to isolate axons from other species to the isolation of human myelin-free axons and determination of their lipid composition, perfection of a procedure for the isolation of axolemma via myelinated axons in bovine brain, an investigation of the ability of isolated bovine myelin-free axons and axolemma to synthesize cerebroside and sulfatide, development of a procedure to simultaneously isolate perikarya, axons, axolemma and myelin from rat brain, an investigation in rats of the turnover of sphingolipids in the perikarya, axons, axolemma and myelin of rat brain, developmental changes in the lipid composition of rat axons, axolemma and myelin, and an investigation of the relationship of axonal, axolemmal and myelin glycoproteins during myelination in the rat brain.